title: Caspase-1 activity in microglia stimulated by pro-inflammagen nanocrystals.
abstract: Although caspase-1 is a key participant in inflammation, there is no sensitive assay to measure its enzymatic activity in real time in cells or animals. Here we describe a nanosensor for caspase-1 ratiometric measurements, consisting of a rhodamine-labeled, caspase-1 cleavable peptide linked to quantum dots (QDs). Microglia cells were stimulated by lipopolysaccharide (LPS) and by hybrid nanoparticles LPS-QDs. These stimuli activated caspase-1 in microglia monolayers and in the mouse brain, while a selected caspase inhibitor markedly reduced it. LPS-QDs entered into the lysosomal compartment and led to an enlargement of these cellular organelles in the exposed microglia. Both lysosomal swelling and mitochondrial impairment contributed to caspase-1 activation and to the consequent interleukin-1β release. The results from these studies highlight how the unique properties of QDs can be used to create versatile biotools in the study of inflammation in real time in vivo.
authors.affiliation: Faculty of Pharmacy and ‡Department of Chemistry, Université de Montréal , CP 6128 Succursale Centre Ville, Montreal, Quebec H3C 3J7, Canada.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Moquin
authors.forename: Eliza
authors.initials: E
authors.lastname: Hutter
authors.forename: Angela O
authors.initials: AO
authors.lastname: Choi
authors.forename: Armen
authors.initials: A
authors.lastname: Khatchadourian
authors.forename: Annie
authors.initials: A
authors.lastname: Castonguay
authors.forename: Françoise M
authors.initials: FM
authors.lastname: Winnik
authors.forename: Dusica
authors.initials: D
authors.lastname: Maysinger
mesh_terms: D000818:Animals; D020170:Caspase 1 / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival; D004789:Enzyme Activation; D007249:Inflammation; D053583:Interleukin-1beta / Q000378:metabolism; D008070:Lipopolysaccharides / Q000737:chemistry; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D045663:Quantum Dots
chemical_list: D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D020170:Caspase 1